JPA: Give a name to a Foreign Key on DB?

Question

I have a simple questions. How can I give a name to the Foreign Key relations that arise from the @ ManyToOne annotation ?

Answer 1

With JPA 2.1 you can just do this with the foreignKey annotation:

import javax.persistence.ForeignKey;
import javax.persistence.JoinColumn;
import javax.persistence.ManyToOne;

@ManyToOne
@JoinColumn(name = "company_id", nullable = false, foreignKey = @ForeignKey(name="FK_COMPANY__ROUTE"))
private Company company;

Do not confuse with the deprecated hibernate equivalent

Answer 2

As of JPA 2.1 it is possible to define foreign keys via @ForeignKey annotation.

Unfortunately, it is not very useful if you only need to change the name. If you specify custom name of the FK, you also have to specify SQL definition of the FK. That is at least the way it works in EclipseLink 2.5.0.

Answer 3

If you are interested in naming the column used in the foreign key, one may specify the name of the column used to create the foreign key, using the @JoinColumn annotation along with the @ManyToOne annotation. The value of the name attribute of the @JoinColumn annotation is used by the JPA provider to map the column name in the table to the entity's attribute.

However, the name of the foreign key constraint created itself cannot be configured. At the time of writing this, it is not possible to specify the name of the foreign key constraint using a JPA annotation or configuration parameter in the OR mapping files. If you need to change the name of the foreign key constraint, then you must create the DDL statement yourself, instead of relying on the JPA provider to do this.